1. Field of the Invention
The present invention relates to an optical module used for optical communication, and more particularly, to an optical module which can increase a mounting area on a stem and compensate for impedance.
2. Background Art
In recent years, an optical transmission system of 10 Gbps is becoming commercially practical and research and development thereof is underway in every place. An optical module which builds such an optical transmission system achieves impedance matching by adjusting the diameter of a lead which passes through a stem (e.g., see Japanese Patent Laid-Open No. 4-365381 or Japanese Patent Laid-Open No. 2004-319984).
To secure a mounting area on a stem, a conventional optical module adopts a glass sealing section of the stem with a hole having a small diameter. This involves a problem that the glass sealing section has impedance of 20 to 30Ω, not an ideal value of 50Ω, resulting in an impedance mismatch.